The invention relates to a glazing assembly for protecting against fire made of at least two panes connected together using a spacer adhesively bonded to the panes and of a water-comprising intermediate layer which fills the intermediate space between the panes. The invention also relates to a mastic composition capable of being used to form an adhesively-bonded spacer.
Glazing assemblies for protecting against fire of this type are known, for example from the document EP 0 590 978 A1. In the case of these known glazing assemblies for protecting against fire, the spacer is composed of a rigid material, namely made of metal or of ceramic, and the adhesive bonding of the spacer to the panes is carried out using adhesive tapes made of synthetic rubber, in particular made of butyl rubber. In addition, the peripheral joint between the spacer and the edges of the panes is rendered leaktight by virtue of an adhesive leaktightness body.
Glazing assemblies for protecting against fire having the abovementioned structure are also known from the document Pat. Abstr. of Japan, C 1187, Apr. 7, 1994, volume 18, No. 198. In the case of these glazing assemblies for protecting against fire, use is made, as spacer, of a shaped tape made of acrylic polymer. The shaped tape is provided, on the sides bearing on the panes, each time with an adhesive layer based on acrylic resin. The acrylic polymers have a relatively low softening temperature and also a relatively low decomposition temperature. In the event of fire, they form unpleasant and troublesome gases.
During the manufacture of known glazing assemblies for protecting against fire, the installation of the shaped sections or shaped tapes forming the spacer requires considerable manual labour. For this reason there is keen interest relating to the use of known processes (see, for example, document DE 2555383 C3) for the manufacture of insulating panes, for the purpose of the manufacture of the abovementioned glazing assembly for protecting against fire, during which the spacer is applied by extrusion in the form of a continuous string of material over the peripheral region of a pane, using an appropriate extrusion device. However, in this case, it turned out that known materials are not appropriate for the present application.
The glazing assemblies for protecting against fire of the abovementioned type are frequently composed of three to five panes and, correspondingly, of two to four intermediate spaces, each time with a spacer and a water-comprising filling. During the manufacture of multilayer glazing assemblies for protecting against fire of this type, each time after the application of a spacer, the following pane is positioned and, using a mechanical press, the pile of layers is compressed to the set thickness desired for the intermediate space. This set thickness for the intermediate space must not be modified when, after the application of the following spacer, the pile of layers is subjected to a further compression procedure, to compress the following intermediate space to the set thickness desired. Furthermore, the spacers must retain their stability and their function even in the event of fire. The physical and chemical properties of a thermoplastic material intended for the spacers are consequently required to meet various requirements, which are not satisfied by the materials known for similar applications.
The fundamental object of the invention is to develop and to make available material compositions which satisfy the special requirements relating to the machine manufacture of glazing assemblies for protecting against fire of the abovementioned type. These materials must in particular, first, be able to be extruded using commercial machines and be able to make possible the plastic deformation necessary during the following compression procedure. However, they must, secondly, exert a sufficient internal strength and a sufficient internal stability and must no longer modify, after the first compression procedure, during the following compression procedures, the transverse cross sectional size at which they have already arrived.
In accordance with the invention, this object is achieved in that the spacer is composed of a string, applied by extrusion over the peripheral region of a pane, made of a butyl polymer comprising from 40 to 65% by weight polyisobutylene, from 10 to 25% by weight of carbon black and from 10 to 40% by weight of a filler, and in that the composition is chosen within this range so that the butyl polymer exhibits, at a temperature of 80xc2x0 C., a transverse or shear modulus of elasticity G* of 1.2 to 2.2 MPa.
Advantageously, the spacer is composed of a butyl polymer which comprises from 30 to 60% by weight of polyisobutylene, from 12 to 18% by weight of carbon black and from 25 to 35% by weight of filler and which exhibits, at 80xc2x0 C., a transverse or shear modulus of elasticity G* of 1.8 MPa.
Substances which do not comprise enclosed portions of air are appropriate as fillers. This is because it turned out that, after filling with the water-comprising poured mass, air adsorbed in the fillers can escape into the intermediate spaces during the subsequent curing process and can form troublesome air bubbles therein. In addition, the desorption of air or other gases releases, at the surface or in the pores, sites capable of taking up a substantial portion of the water of the intermediate layer, which loses its fireproofing protective properties.
According to an advantageous alternative form, the filler comprises at least one substance which undergoes an endothermic reaction when it is brought to a temperature of at least 180xc2x0 C. Thus, the filler exerts a cooling effect on the spacer which has a favourable influence on the resistance to fire. In fact, an endothermic reaction temperature from 130 or 150xc2x0 C. will also be advantageous but will also be incompatible with the temperatures for manufacturing and processing butyl rubber.
This endothermic reaction preferably consists of the release of water of hydration or of crystallization.
The reaction advantageously does not release, apart from the water, a substance which is a gas at the reaction temperature.
The filler can be chosen from inorganic or organic substances or their mixtures.
Oxides, hydroxides or salts of sulphates, sulphites, phosphates, hydrogenphosphates, phosphites, hypophosphites, silicates, nitrates, nitrites or carbonates are taken into consideration as inorganic fillers. Mention may be made, for example, of MgO, CaSO4, in particular hydrate, such as CaSO4.2H2O, MgSO4, in particular hydrate, such as MgSO4.7H2O, iron(II) or (III) sulphate, in particular hydrate, such as Fe2(SO4)3.9H2O, sodium sulphite, in particular hydrate, such as Na2SO3.7H2O, CaCO3, MgCO2, K2CO3, in particular hydrate, such as K2CO3.2H2O, silicates, Al(OH)3, Mg(OH)2, Al2O3, aluminium or magnesium phosphates, in particular Mg(H2PO4)2.8H2O, salts of phosphorous acid derived in particular from manganese, in particular hydrate, such as MnHPO3.H2O, manganese hypophosphite, in particular hydrate, such as Mn(H3PO2)2.H2O, CaNO2, in particular hydrate, such as CeNO3.3H2O, or other inorganic substances having the properties mentioned.
Salts of organic acids, such as citrates, in particular sodium citrate pentahydrate, tartrates, in particular sodium tartrate dihydrate, mesotartrates, in particular calcium mesotartrate trihydrate, or glyconates, in particular calcium d-glyconate monohydrate, are taken into consideration as organic filler.
The special compositions according to the invention are to be chosen, within the ranges indicated above of the chemical composition of the main constituents of the butyl polymer, so that the transverse modulus of elasticity of the material lies, at a temperature of 80xc2x0 C., within the range from 1.2 to 2.2 MPa. It is only when this condition is met that the material can, first, be extruded using conventional extrusion equipment and that, secondly, it has a consistency and a strength and a capacity for deformation such that it can be compressed to the set size of the space without difficulty during the first compression procedure, while no longer modifying its set dimensions during subsequent compression procedures.
For the reasons set out, namely, first, for reasons of processability using extrusion equipment and, secondly, because of the low ability to deform required after obtaining the final geometry, the material must exhibit proportions of elastic and plastic deformation within entirely specific ratios, which can be defined as material constant by the transverse or shear modulus of elasticity G*. The transverse modulus of elasticity G*, which represents a measurement of the viscoelastic properties of an elastomer, is treated, in the case of dynamic mechanical measurements, in accordance with the equation G*=Gxe2x80x2+iGxe2x80x3, as a complex quantity, Gxe2x80x2 denoting what is known as the xe2x80x9cstorage modulusxe2x80x9d, for the purpose of the characterization of the proportion of elastic deformation, and Gxe2x80x3 what is known as the xe2x80x9closs modulusxe2x80x9d, for the purpose of the characterization of the proportion of plastic deformation.
The transverse modulus of elasticity G* is determined using an oscillating measurement system, for example using two coaxial cylinders, which contain, in the annular passage between the external cylinder and the internal cylinder, the material to be determined. An oscillatory movement, variable in frequency and in amplitude, is applied to one of the two cylinders on this occasion. The oscillatory movement transmitted to the other cylinder certainly has the same frequency but, however, displays another amplitude according to the viscoelastic properties of the material to be determined and exhibits, with respect to the oscillation of the driven cylinder, a more or less significant phase shift. The transverse modulus of elasticity G* can be determined by a corresponding mathematical treatment of the inlet and outlet signals of the measurement device.
The thermoplastic butyl polymers suitable for the application according to the invention have, according to the temperature, the following rheological properties:
Another subject-matter of the invention is a mastic composition based on butyl rubber as described above.
This composition can be used in particular for preparing spacers in multiple glazing assemblies which may or may not be filled with an intermediate layer, which can be an aqueous gel, for manufacturing a fireproof glazing assembly, but also a resin, for manufacturing a solar cell, or in laminated glazing assemblies including a plastic insert, in particular made of polyvinylbutyral (PVB).
It can also be used for the sealing, pointing or fitting of sheets of glass and various materials, optionally in combination with a conventional material, such as polysulphide.
The invention is described in more detail subsequently with reference to two implementational examples for the purpose of the manufacture of multilayer glazing assemblies for protecting against fire having intermediate layers comprising water and spacers applied by extrusion starting from a thermoplastic butyl polymer.